AS5304 Magnet Specification Magnetic Multipole Ring, MR20-44 Pole Length 2.0 mm, 44 Poles 1 General Description This specification defines the dimensional and magnetic properties of a multipole magnetic ring for use with the AS5304 magnetic encoder for off-axis rotary applications. Figure 1 AS5304 with multipole ring magnet for off-axis rotary motion sensing (not to scale) Note: The MR20-44 magnet contains only the magnetic ring (see picture on the right), the metal carrier is shown for illustration purposes only 2 Multipole Ring Magnets for the AS5304 Figure 2 shows the proper placement of a multipole ring over the AS5304. The centerline of the magnetic ring (median Hall sensor scan path) is located over the Hall array (see Figure 3). The magnetic ring is designed such that the pole length lp matches the required length at the scan path (typically the center) of the ring. The IC is oriented in perpendicular with respect to the rotation center. The correct measurement radius can be calculated by the number of poles of the magnet ring and the specified pole length: These figures can be determined by the code of the magnet: AS5304 Magnet Specification 2013-Sep [1-00] page 2/7 MR20-44 Number of poles M: Magnet Nominal pole length in 1/10 mm AS5304 = 20 (2.0mm) AS5306 = 12 (1.2mm) R: Ring S: Strip The correct measurement radius for the MR20-44 magnet ring is therefore: rm = pole _ length(mm) * number _ of _ poles 2 *π rm = 2.0 * 44 = 14.00mm 2 *π Figure 2 Proper placement of the ring magnet (not to scale) lp ro r i rm median Hall sensor scan path AS5304 Magnet Specification 2013-Sep [1-00] page 3/7 3 Locating the Hall Sensor Array The measurement radius should coincide with the Hall sensor array on the chip. The location of the Hall sensors can be seen in Figure 3. The Hall sensor array is located 1.02mm above the horizontal centerline of the TSSOP-20 package, or 3.20mm + 1.02mm = 4.22mm above the edge of pins #1….10 (top view, pin#1 at bottom left). Figure 3 Location of Hall sensors in the TSSOP-20 package 0.2299±0.100 1.02 Die C/L 3.200±0.235 0.2341±0.100 Package Outline 0.7701±0.150 3.0475±0.235 4 Dimensional Specification Magnet Order # AS5000-MR20-44 on ams web shop www.ams.com/ICdirect Parameter Sym bol Min Typ Max Unit Magnet material Plastic bonded Strontium Ferrite SrFe. Supplier-internal material grade = BMNP-1612. Remanence Br Pole length lp 280 300 2.0 Number of poles Inner ring radius Note mT mm Suited for AS5304 44 ri 11.975 Resolution 12 12.025 3520 Res Measurement radius rm Outer ring radius ro AS5304 Magnet Specification 15.975 mm step s/rev 11.78 bit 880 ppr 14.00 mm 16 16.025 2013-Sep [1-00] With AS5304 @ 160x interpolation Pole length* number of poles / 2π mm page 4/7 Strip thickness d 1.5 1.5 1.6 mm Magnetic amplitude Amag 52 76 89 mT 25 mT Amplitude variation Temperature range Tamb Tbd °C Magnetic temperature drift Tdmag Tbd %/K 5 Mechanical Drawing 6 Marking Measured at magnet surface The magnet ring has two marks at the backside: One mark shows the number of poles (44) the other mark shows a single digit letter (A…F), which is of no relevance. AS5304 Magnet Specification 2013-Sep [1-00] page 5/7 Figure 4 Markings at the backside of the magnet 7 Mounting the Magnet Ring As mentioned in chapter 5, the magnet ring has two markings, which represent the backside of the ring. The front side should be facing the AS5304 IC with a gap of <lp/2 = <1.0mm. The magnet ring may be mounted directly on magnetic or non-magnetic surfaces. When magnetic surfaces are used, the ring may be mounted on top of the surface, but not immersed in a cavity, as this may weaken the magnetic field of the magnet. When mounting the magnet on a non-magnetic surface, either method is acceptable. Depending on the carrier material, there are several adhesives available to glue the ring to the surface. For general ruggedness and vibration demands, the use of two-component-adhesive (binder + hardener) has proven to be successful in most cases. For more rigid demands, magnet suppliers offer customized solutions where the magnet material is directly overmolded on the carrier, e.g. a shaft, bushing, plate, etc. Please contact your magnet supplier for more information. A list of recommended suppliers is available for download on the ams website. 8 Magnet Supplier Information Bomatec AG Hofstrasse 1 CH-8181 Höri Tel. +41 44 872 10 00 www.bomatec.ch AS5304 Magnet Specification 2013-Sep [1-00] page 6/7 Copyrights Copyright ams AG, Tobelbader Strasse 30, 8141 Unterpremstaetten, Austria-Europe. Trademarks Registered. All rights reserved. The material herein may not be reproduced, adapted, merged, translated, stored, or used without the prior written consent of the copyright owner. Disclaimer Devices sold by ams AG are covered by the warranty and patent indemnification provisions appearing in its Term of Sale. ams AG makes no warranty, express, statutory, implied, or by description regarding the information set forth herein. ams AG reserves the right to change specifications and prices at any time and without notice. Therefore, prior to designing this product into a system, it is necessary to check with ams AG for current information. This product is intended for use in commercial applications. Applications requiring extended temperature range, unusual environmental requirements, or high reliability applications, such as military, medical life-support or life-sustaining equipment are specifically not recommended without additional processing by ams AG for each application. This Product is provided by ams “AS IS” and any express or implied warranties, including, but not limited to the implied warranties of merchantability and fitness for a particular purpose are disclaimed. ams AG shall not be liable to recipient or any third party for any damages, including but not limited to personal injury, property damage, loss of profits, loss of use, interruption of business or indirect, special, incidental or consequential damages, of any kind, in connection with or arising out of the furnishing, performance or use of the technical data herein. No obligation or liability to recipient or any third party shall arise or flow out of ams AG rendering of technical or other services. Contact Information Headquarters ams AG Tobelbaderstrasse 30 8141 Unterpremstaetten Austria, Europe Tel: +43 (0) 3136 500 0 Website: www.ams.com For Sales Offices, Distributors and Representatives, please visit: www.ams.com/contact AS5304 Magnet Specification 2013-Sep [1-00] page 7/7